gray goldenrod

Goldenrod

Description

About 100 perennial species make up the genusSolidago, most being found in the meadows and pastures, along roads, ditches and waste areas in North America. There are a handful of species from each of Mexico, South America, and Eurasia. Some American species have also been introduced into Europe some 250 years ago.

Many species are difficult to distinguish. Probably due to their bright, golden yellow flower heads blooming in late summer, the goldenrod is often unfairly blamed for causing hay fever in humans. The pollen causing these allergy problems is mainly produced by Ragweed (Ambrosia sp.), blooming at the same time as the goldenrod, but is wind-pollinated. Goldenrod pollen is too heavy and sticky to be blown far from the flowers, and is thus mainly pollinated by insects.

Goldenrods are easily recognized by their golden inflorescence with hundreds of small capitula, but some are spike-like and other have auxiliary racemes.

They have slender stems, usually hairless but S. canadensis shows hairs on the upper stem. They can grow to a length between 60 cm and 1.5 m.

Their alternate leaves are linear to lanceolate. Their margins are usually finely to sharply serrated.

Propagation is by wind-disseminated seed or by underground rhizomes. They form patches that are actually vegetative clones of a single plant.

Use and cultivation

Goldenrod is used as a food plant by the larvae of various Lepidoptera species (see list of Lepidoptera that feed on goldenrods). The invading larva induces the plant to form a bulbous tissue mass (called a gall) around it, upon which the larva then feeds. Various parasitoid wasps find these galls, and lay eggs in the larvae, penetrating the bulb with their ovipositor. Woodpeckers have learned to peck open the galls and eat the insect in the center.

Goldenrods can be used for decoration and making tea. Goldenrods are, in some places, held as a sign of good luck or good fortune; but they are considered weeds by others.

Goldenrods are mostly short-day plants and bloom in late summer and early fall and some species produce abundant nectar when moisture is plentiful before bloom, and the bloom period is relatively warm and sunny. Honey from goldenrods often is dark and strong due to admixtures of other nectars. However when there is a strong honey flow, a light (often water white), spicy-tasting honey is produced. While the bees are ripening the honey there is a rank odor and taste, but finished honey is much milder.

Garden use

British gardeners adopted goldenrod long before Americans. Goldenrod only began to gain some acceptance in American gardening (other than wildflower gardening) during the 1980s. A hybrid with aster, known as x Solidaster is less unruly, with pale yellow flowers, equally suitable for dried arrangements.

Solidago canadensis was introduced as a garden plant in Central Europe, and is now common in the wild. In Germany, it is considered an invasive species that displaces native vegetation from its natural habitat.

Goldenrod is a companion plant, playing host to some beneficial insects, and repelling some pests.

Industrial use

Inventor Thomas Edison experimented with goldenrod to produce rubber, which it contains naturally. Edison created a fertilization and cultivation process to maximize the rubber content in each plant. His experiments produced a 12 foot tall plant that yielded as much as 12 percent rubber. The rubber produced through Edison's process was resilient and long lasting.
The tires on the Model T given to him by his friend Henry Ford were made from goldenrod. Examples of the rubber can still be found in his laboratory, elastic and rot free after more than 50 years. However, even though Edison turned his research over to the U.S. government a year before his death, goldenrod rubber never went beyond the experimental stage.

Medicinal use

The variety Solidago virgaurea is used as a traditional kidney tonic. It is used by practitioners of herbal medicine as an agent to counter inflammation and irritation of the kidneys when bacterial infection or stones are present. Goldenrod has also been used as part of a tincture to aid in cleansing of the kidney/bladder during a healing fast, in conjunction with Potassium broth and specific juices. 'Solidago odora' is also sold as a medicinal, for these issues: mucus, kidney/bladder cleansing and stones, colds, digestion.

In Midwestern states in the mid-twentieth century it was said that when the goldenrod bloomed, it would soon be time to go back to school--the blossoms appeared in mid- to late August, shortly before the traditional start of school on the day after Labor Day.

In Sufjan Stevens' song, Casimir Pulaski Day, the narrator brings goldenrod to his girlfriend upon finding out that she has been diagnosed with bone cancer. Carrie Hamby's song, Solidago, tells the story of Thomas Edison's experiments with making goldenrod a domestic source of rubber during the 2nd world war.

The Sweet Goldenrod (Solidago odora) is also the state herb of Delaware as of June 24, 1996.